Influence of Expansion Joints in Deck Parapets on Localized Cracking in Adjacent Box Girders

Abstract

Concrete adjacent box girders are widely used in short- and medium-span highway bridges. Effects of bridge accessories, such as curbs and parapets, on the structural performance are commonly ignored in design, health monitoring, and evaluation. The standard practice is to provide expansion joints in the parapet wall for reasons of temperature differentials, shrinkage, and settlement. Lack of knowledge on the influence of expansion joints in bridge accessories may have serious consequences in engineering practice. The Yangsi Highway Bridge located in Zhejiang, China, experienced extensive L-Type cracking on the edges of the exterior box girders concentrated below the expansion joints. In order to investigate the observed phenomena, 3D finite-element models were developed to investigate the relationship between the L-Type cracking and the presence of the expansion joint. Significant stress concentration was observed at the edge of the exterior box girder below the expansion joint. The analysis revealed a unique cracking mechanism based on the consistent deflection response and was validated with experimental tests. Parametric analyses were finally conducted to provide important insights into the factors that influence the stress concentration.